Apparatus for belling plastic pipe

ABSTRACT

Method and apparatus for belling an end of a length of thermoplastic pipe by thermally softening the end of the pipe, inserting an expansible belling head into the softened end, expanding the belling head to accomplish shaping of the thermoplastic material, cooling the pipe, and then separating the pipe from the belling head.

This is a division of application Ser. No. 41,267, filed May 28, 1970,and issued on Oct. 7, 1975 as U.S. Pat. No. 3,910,744.

This invention relates to a unique method and apparatus for bellingpipe, and particularly to a method and apparatus for belling pipe ortubing formed from a heat softenable thermoplastic material.

Rigid thermo-plastic pipe is now manufactured in many different sizesand is used extensively in lieu of metal pipe. Rigid plastic pipe isusually formed by extrusion, and is cut into lengths to facilitatestorage and handling. Connecting sections of the pipe is an expensiveand time consuming operation unless one end of each section of pipe hasa bell end or socket to receive the other end of an adjacent pipe. Thepipe sections can then be readily connected together and cemented, ifdesired, to form a fluid-tight joint.

In accordance with one embodiment of this invention, a bell end isformed on a length of pipe as the pipe is conveyed laterally through aplurality of work stations. At one station an end of the pipe is cleanedby an air blast and is heated to the softening temperature of theplastic material. The pipe is then transferred to a belling stationwhere the heat softened end of the pipe is expanded to form a bell endof the required dimensions. The bell end is formed by forcing a mandrelof an exterior configuration the same as the interior of the desiredbell end into the heat softened end of the pipe and then cooling the endof the pipe prior to withdrawing the mandrel. Then, the mandrel iswithdrawn from the belled end of the pipe. The mandrel is so formed thatit contracts as it is withdrawn from the pipe and correspondingly, themandrel is readily removable from the pipe.

In one preferred embodiment of this invention, the pipe is transportedlaterally to the heating and bell forming stations by a continuouslydriven conveyor. Automatically actuated stops position the pipe at theheating station in alignment with a heating drum that is moved to aposition surrounding the end of the pipe. At the belling stationautomatically actuated stops initially position the pipe and inaddition, a cradle lifts the pipe from the conveyor to a position inwhich the heated end is aligned with the belling mandrel. The entireoperation is performed automatically and requires no manual manipulationor intervention.

In another embodiment of the invention, the pipe is heated, belled, andcooled at a single station where the several operations are performedautomatically and no manual assistance is required.

A unique mandrel is used to bell or expand the heat softened end of thepipe. The mandrel has expandable slip segments which, in the expandedcondition present an external surface configuration corresponding to theinternal configuration of the bell to be formed on the end of the pipe.The slip segments are arranged for axial movement along a conicalportion of the mandrel. The arrangement is such that the slip segmentsare free to slide axially along the cone shaped portion of the mandrel.Hence, when the belling head is forced into the heat softened end of thepipe, the slig segments move axially to the expanded position and form abell of the desired diameter and configuration on the end of the pipe.During movement of the mandrel into the pipe, the pipe is firmly heldagainst axial movement by a fence which engages its opposite end.Advantageously, the cone shaped portion of the mandrel has an angle withthe axis of the mandrel that is sufficiently small that the slipsegments do not tend to slide axially as a result of forces due toshrinking of the pipe end during cooling. After the bell is formed andthe pipe end is cooled, movement of the belling head out of the pipecauses the slip segments to contract so the pipe is released from themandrel.

A unique control assures the forming of a bell of precisely the samelength on each pipe processed even though the length of successivesections of pipe may vary somewhat. This is accomplished byautomatically terminating forward movement of the mandrel into the pipein response to full seating of the mandrel in the pipe. Duringwithdrawal of the mandrel, the clamping cylinder holds the pipe againstaxial movement with the belling mandrel.

Advantageously, the steps of heating, belling, and cooling arecontrolled in timed relation to each other so a perfect bell of the samesize and length is formed on the end of each pipe passed through thebelling apparatus. A simple, yet efficient stop system, includingretractable and extendable stop rods or pins, assure proper positioningof the pipe at each work station of the belling apparatus.

Correspondingly, an object of this invention is a method and apparatusfor belling plastic pipe capable of being softened.

Another object is a method and apparatus for forming a bell end on heatsoftenable thermo-plastic pipe to facilitate connecting sections of thepipe in end to end relation.

Another object is a method and apparatus for belling plastic pipe inwhich the entire operation is completely automatic and requires nomanual effort or intervention.

Another object is an apparatus for belling pipe in which the pipetransporting conveyor is vertically adjustable to facilitate adjustingand adapting the apparatus to bell pipe of at least several differentdiameters.

A further object is a method and apparatus for belling plastic pipe inwhich the pipe is transported laterally through the apparatus, isprecisely position at work stations via automatic retractable stopmeans, is rotated by the transporting conveyor while being restrainedagainst transverse movement by the stop means at a heating station, sothe end of the pipe is uniformly heated and softened, is gripped andlifted at the belling station to a position in precise alignment withthe belling mandrel, is cooled prior to removal from the bellingmandrel, and includes provision for assuring the same length anddiameter of bell on each pipe processed regardless of normal variationsin the length of the pipe sections passed through the apparatus.

A further object is a pipe belling device in which the pipe bellingmandrel is pressed into the softened end of a pipe, and in which thebelling mandrel has an expandable slip segment section which contractsautomatically in response to axial movement of the belling mandrel outof the end of the belled pipe.

Numerous other objects, features, and advantages of this invention willbecome apparent with reference to the drawings which form a part of thisspecification, and in which:

FIG. 1 is a simplified plan view of a first embodiment of the bellingapparatus of this invention;

FIG. 2 is a front elevational view of the belling apparatus of FIG. 1,with portions of the apparatus cut away;

FIG. 3 is an end elevational view of the belling apparatus of FIG. 1,with portions thereof cut away;

FIG. 4 is a partial view showing the mechanism for operating the pipelifting cradles at the belling station;

FIG. 5 is a rear elevational view of the heating head assembly andbelling head assembly;

FIG. 6 is a front elevational view of the heating head without itssupporting cradle;

FIG. 7 is a transverse sectional view of the heating head taken alongline 7--7 of FIG. 6;

FIG. 8 is a partial front elevational view of the belling head;

FIG. 9 is a view in section taken along line 9--9 of FIG. 7, and showinga belled pipe fully seated on the belling head;

FIG. 10 is a view corresponding to FIG. 9, but showing the position ofthe parts of the belling head when the belling head is partiallywithdrawn from the bell end of a pipe;

FIG. 11 is a diagrammatic view of the control system for the firstembodiment of the belling apparatus of this invention;

FIG. 12 is a top plan view of a second embodiment of the bellingapparatus of this invention;

FIG. 13 is a side elevational view taken along line 13--13 of FIG. 12;and

FIG. 14 is an end elevational view taken along line 14--14 of FIG. 13.

Referring now to the drawings, and particularly to FIG. 1, there isshown in simplified form a first embodiment of the pipe bellingapparatus of this invention. In this embodiment, the belling apparatus 1includes a positioning station 2, a heating station 3, and a bellingstation 4. As shown, there is a length of plastic pipe 5 at positioningstation 2, a length of thermo-plastic pipe 6 at heating station 3, and alength of thermo-plastic pipe 7 at belling station 4. The pipe is movedintermittently and sequentially to stations 2, 3 and 4 in a directiontransversely of its length by a continuously driven conveyor belt havinga pair of spaced apart parallel belts 8 and 9.

Lengths of pipe are fed one by one onto the conveyor belts by an infeedconveyor system including a pivoted pipe transfer device 10 and aconveyor 11 which feeds a length of pipe onto the pipe transfer device.Actuation of pipe transfer device 10 causes a length of pipe to bedeposited on conveyor belts 8 and 9. The conveyor belts transport thepipe to positioning station 2. During the travel of the pipe to thepositioning station, the pipe is guided axially of its length by frontfence 12 and rear fence 13, which assure that the pipe on the conveyoris properly positioned axially.

At heating station 3 there is a hollow cylindrical heating head 14. Theheating head is movable to the extended dotted line position and to theretracted solid line position shown at FIG. 1 by a motor in the form ofair cylinder 15. In the extended or advanced (dotted line) position theheating head extends around the front end 16 of pipe 6 at heatingstation 3.

At belling station 4 there is a belling head 17. The belling head isadvanced and retracted by a motor in the form of air cylinder 18.Mounted on the belling head at a location in front of stop flange 19 isa cooling ring 20 of a diameter greater than the diameter of the bell tobe formed on the largest diameter of pipe to be handled by theapparatus. Cooling ring 20 is provided with a plurality of nozzlesdirected toward the belling head and through which air is forced to coolthe end of the pipe after a bell is formed on the pipe.

At belling station 4 there are a pair of lift cradles 21 and 22 locatedrespectively on opposite sides of belts 8 and 9. Lift candles 21 and 22normally occupy a retracted position below the top of conveyor belts 8and 9, but are extendable to lift a pipe at station 4 upwardly, out ofengagement with the conveyor belts, and into precise axial alignmentwith belling head 17. A clamp 23, above and vertically aligned withcradle 22, is arranged to clamp the pipe against cradle 22, when aircylinder 24 is actuated.

Transverse movement of the pipe through the belling apparatus to theseveral stations 2-4 is controlled by stop rods, two of which arelocated at each of the stations. As shown at FIG. 1, the stop rods 25and 26 are in spaced apart relation at station 2. Stop rods 27 and 28are in spaced apart relation at station 3, and stop rods 29 and 30 arein spaced apart relation at station 4. Each pair of stop rods is movablesimultaneously from an extended position in which the rods project intothe path of travel of a pipe on conveyor belts 8 and 9, to a retractedposition in which pipe on the conveyor is released to be transported tothe next station by the conveyor belts. In the extended position of therods, the pipe is merely held against transverse movement, but isrotated by the continuously driven conveyor, at both stations 2 and 3.

As shown at FIGS. 1 and 7, the several embodiments of the pipe bellingapparatus of this invention form a bell shaped end 32 on one end of alength of thermo-plastic pipe. It will be observed with reference toFIG. 7 that end 32 is of the so-called single bell type having anenlarged cylindrical end portion 33 connected to the body 34 of the pipeby a short tapered section 35. While the bell 32 is of the type havingespecial utility for joining together sections of plastic pipe of likediameter, it is to be understood that the belling apparatus of thisinvention can be used to form the so-called "double bell" end, as wellas "adapter" type ends on plastic pipe of various sizes.

SUMMARY - OPERATION

Pipe to be belled is transported longitudinally by conveyor 11 totransfer device 10 and into engagement with stop fence 36, whichpositions the pipe for transfer to belts 8 and 9. The transfer device 10is actuated to transfer the pipe to belts 8 and 9 of the conveyor. Thebelts move the pipe to the position of pipe 5 at FIG. 1 where furthertransverse movement of the pipe by the conveyor belts is prevented bythe extended stop rods 25 and 26. When stop rods 25 and 26 areretracted, the pipe is released and is transported by the conveyor beltsto station 3 where the pipe is again stopped by the stop rods 27 and 28.The action of stop rods 27 and 28 is such that only transverse movementof the pipe 6 is prevented, but the pipe is still resting on theconveyor belts and is therefore rotated by the belts. Stops rods 27 and28 are so positioned that a pipe 6 engaging the rods at station 3 isaxially aligned with heating head 14. The heating head is then advancedto the position shown in dotted lines where it extends around end 16 ofthe pipe. As soon as heating head 14 moves to the advanced position, anair blast of short duration from an air nozzle at the center of theheating head clears chips and other foreign matter from the inside ofthe pipe end 16.

When end 16 of the pipe is sufficiently heated, heating head 14 isretracted, stop rods 27 and 28 are retracted, and the pipe istransported by the conveyor belts to station 4 where its transversemovement is again arrested by stops 29 and 30.

At station 4, the operation is slightly different from the operation atstation 3. At station 4, cradles 21 and 22 are elevated to lift the pipeout of engagement with conveyor belts 8 and 9. In addition, the clamps23 is activated so the pipe is gripped by the cradle 22 and clamp 23.The cradles are so arranged than in the extended position, they positionthe pipe in precise axial alignment with belling head 17. With the pipein the elevated position, belling head 17 is advanced into the heatsoftened end 16 to form the bell end 32 on the end of the pipe. Duringthe forward motion of belling head 17 into the pipe, axial movement ofthe pipe is resisted by engagement of its opposite end 38 with rearfence 13. After belling head 17 is fully seated in the pipe, cooling airis forced through the nozzles of cooling ring 20 to cool the now belledend 32 of the pipe before belling head 17 is withdrawn. When the pipe iscooled to a temperature below its softening temperature, the bellinghead is withdrawn, cradles 21 and 22 are lowered so the pipe again restson conveyor belts 8 and 9, and stop rods 29 and 30 are then retracted toallow the conveyor to move the pipe to the outfeed conveyor 38, whichconveys the pipe away from the bell forming apparatus.

DETAILED DESCRIPTION OF FIRST EMBODIMENT

FIGS. 2-5 show additional details of the first embodiment of the pipebelling apparatus of this invention. As shown at FIGS. 2 and 3, thevarious parts of the belling apparatus 1 are mounted on a rigid mainframe 40 comprised of structural steel elements, such as I beams and Cbeams suitably secured together with bolts, rivets, or by welding, andis supported on vertical legs 41 anchored to the floor 42 of thebuilding where the unit is installed. In addition to the main frame 40,there is also a conveyor supporting subframe 43 supported by the frame40 for vertical movement so the height of the conveyor can be adjusted.Subframe 43 includes a pair of spaced apart conveyor support pedestals44 at the infeed side of the apparatus, and a pair of spaced apartpedestals 45 at the discharge side of the apparatus. The pairs ofpedestals 44 and 45 are arranged in a generally rectangular array withthe respective pedestals 44 at one side of the apparatus alignedrespectively with the pedestals 45 at the other side of the apparatus,and with the respective pairs of pedestals aligned with each otherlongitudinally of the apparatus. Each pedestal includes a pair ofupright, parallel, spaced apart plates 47 and 48, as shown at FIG. 2.Joining plates 47 and 48, along their outer edges, is a vertical slideplate 49 which, in the case of each pedestal, lies in a planetransversely outwardly of the main frame longitudinal beams 49'.

Joining the pairs of pedestals at opposite sides of the apparatus aretwo pairs of transversely extending C beams 50 and 51. The pairs of Cbeams 50 and 51 function to rigidly interconnect each pedestal 44 at oneside of the conveyor with the respective opposed pedestal 45 at theother side of the conveyor. A motor support frame 52 is secured to eachpair of C beams 50 and 51 by a downwardly extending pair of supportmembers 53, 54 formed from angle iron. The motor support frame 52 iselongated, as shown at FIG. 2, and functions to connect the two pairs ofC beams 50 and 51 together and increase the rigidity of conveyorsupporting subframe 43. Mounted at one end of motor support frame 52 isa combined drive motor - reduction gear assembly 55 which drivesconveyor belt 8 and 9. Advantageously, the gear reduction unit is of thevariable speed type to permit adjusting the speed of the conveyor beltsfor optimum operation of the apparatus.

Secured to and projecting outwardly from each slide plate 49 is athreaded bushing 56, as shown at FIG. 3. Threaded into bushing 56 is anelongated adjusting screw 57 with a hand wheel 58 at its lower end. Theadjusting screw extends through a collar 59 fixed to main frame 40. Theconnection between the collar and the adjusting screw is such that thescrew is free to rotate, but is restrained from axial movement.

Each slide plate 49 rises in a T-shaped slot formed in standards 60. Theslot is carefully machined so each plate 49 can be adjusted vertically,but is restrained from movement transversely or longitudinally of theconveyor so the several parts of the conveyor remain in precisealignment during vertical adjustment. While the details of only onestandard have been explained in detail, it is to be understood that allstandards are identical and provide for adjusting the vertical height ofthe conveyor belts 9 and 10 relative to frame 40.

Extending through the pedestals 44 is a drive shaft 61. The drive shaftis journaled for rotation in the pedestals. Secured to drive shaft 60,for rotation with the shaft, are conveyor drive wheels 62 which arelocated respectively between the supporting plates 50 and 51 of thepedestals 44. The drive shaft is driven by the motor - reduction gearunit 55 via suitable sprockets and a drive chain 63. Pedestals 45, atthe opposite side of the apparatus, provide journals for idler wheels64.

Conveyor belt 8 extends around the drive wheel 62 and idler wheel 64 ofthe pedestals at one end of the apparatus, whereas belt 9 extends aroundthe drive pulley and idler pulley of the pedestal at the other end ofthe apparatus. An elongated belt support plate 65 extends under theupper run of each conveyor belt to prevent sagging of the belts and tomaintain the height of the upper portion of the belt constant for anyparticular setting of the conveyor frame. Because of the substantialdistance between the drive wheels 62 and idler wheels 63, this supportis desirable to avoid sagging of the conveyor belts 8 and 9. Theconveyor support plates 65 are secured to the C beams 50 and 51, asshown at FIG. 4. Since pedestals 44 and 45, as well as motor - reductiongear unit 55 are mounted on the same rigid conveyor frame, verticaladjustment of the conveyor can be readily accomplished, even while theconveyor belts are moving, by rotating the adjusting screws 57. Sincethe motor and the conveyor belt supporting pedestals are all mounted onthe same frame, the distance between the motor drive sprocket and thedrive shaft driven sprocket remains constant and hence, there is no needto adjust the chain 62.

As shown at FIGS. 2 and 3, a shaft 66 of a length approximately the sameas the width of the frame 40 extends transversely of the frame and hasits ends suitably journaled as by bearing blocks 67. As shown at FIG. 3,the stop rod 25 and stop rod 27 are secured to shaft 66 so the stop rodsadvance and retract upon rotation of the shaft. Advantageously, theconnection between stop rod 27 and shaft 66 is releasable so the stoprod may be adjusted along the axis of the shaft. Similarly, there is ashaft 68 of the same length as shaft 66, and which has its endsjournaled in bearing blocks 69. Stop rods 26 and 28 are secured to shaft68, the connection between stop rod 28 and the shaft providing foradjustment of this stop rod along the length of the shaft. Secured toshaft 66, at a location between stop rods 25 and 27, is a crank arm 70.A crank arm 71 is similarly secured to shaft 68 at a location betweenstop rod 26 and 28, the two crank arms being aligned longitudinally offrame 40. Crank arm 70 is mechanically connected to crank arm 71 by apush rod 72, so shafts 66 and 68 rotate in unison. Stop rod operatingcylinder 73 has one end pivotally connected to main frame 40 at a pivotconnection 74. The piston rod end is pivotally connected to rod 72 atpivot connectiion 75. As shown at FIGS. 2 and 3, stop rods 25 - 28 arein their extended positions. Operating cylinder 73 rotates stop rods25 - 28 in a clockwise direction simultaneously to move the rods to aretracted position in which they are beneath the level of the uppersurfaces of conveyor belts 8 and 9.

Stop rods 29 and 30 are not secured to the respective shafts 66 and 68,but instead are mounted for pivotal movement relative to the respectiveshafts. The connection between the shaft and the stop rods includes acollar to which the rod is connected and which functions as a bearingfor movement of the stop rods relative to the shaft. Secured to thecollar for each stop rods 29 and 30 is a downwardly extending crank arm77 (FIG. 3). The ends of the respective crank arms 77 for stop rods 29and 30 are interconnected for simultaneous pivotal movement by a pushrod (not shown) identical to the push rod 72 previously explained. Theend of the push rod is pivotally connected to a motor, namely, thepneumatic cylinder 78, shown at FIG. 3. By virtue of this arrangement,it is apparent that stop rods 29 and 30 move simultaneously uponoperation of cylinder 78, and that this motion is independent of themotion of stop rods 25 - 28.

FIGS. 3 and 4 show the details of the cradles 21 and 23, and theoperating mechanism for these cradles. As shown at FIGS. 1 and 4,cradles 21 and 23 are located on opposite sides of conveyor belts 8 and9. Cradles 21 and 23 are identical, and as shown at FIG. 3, the upperend of each cradle takes the form of a V block 80 having inwardlysloping upwardly facing surfaces which prevent a pipe from rolling offthe cradle and which assures precise positioning of the pipehorizontally, relative to the belling head, when the cradles areelevated to lift a pipe. Secured to and extending downwardly from Vblock 80 is a threaded sleeve 81 (FIG. 4). The threaded sleeve providesfor mounting the V block 80 on the threaded upper end of an elevatingshaft 82, for vertical adjustment. A lock nut 83 provides for securingthe cradle to the shaft at the adjusted position. The elevating shaft 82for cradle 21 extends through a guide bushing 84 secured to the mainframe with its axis vertical. Similarly, the elevating shaft 82 ofcradle 23 extends through a guide bushing 86. Extending transverselythrough the lower end of each elevating shaft 82 is a pin 87 whichengages in slots 88 of a pair of parallel crank arms 89, 90 of a bellcrank assembly 91, and between which arms the elevating shaft extends.Bell crank assembly 91 is mounted for pivotal movement on a shaft 92,and includes an upwardly extending crank arm 93. Arms 93 are pivotallyconnected respectively to the opposite ends of a push rod 94. Pneumaticcylinder 95, offset to one side of rod 94, is pivotally connected to themain frame at one end and is pivotally connected to push rod 94 at itsother end. The arrangement is such that when cylinder 95 is operated,its piston rod extends, and cradles 21 and 23 are simultaneously movedto the elevated dotted line positions shown at FIGs. 3 and 4, in which apipe lifted by the cradles is above the level of conveyor belts 8 and 9.

As shown at FIGS. 2-4, the assembly including clamp 23 and air cylinder24 is supported on an L-shaped support structure 100 secured to one endof main frame 40. Clamp 23 takes the form of a V block of the same sizeas the V block 80 which forms the upper end of cradles 21 and 22. Clamp23 and cradle 22 are vertically aligned with each other.

Heating head 3 and belling assembly 4 are supported at the same end ofmain frame 40 as front fence 12. The support for belling assembly 4(FIGS. 2 and 5) includes a pedestal 101 secured to main frame 40.Secured to the pedestal is pneumatic cylinder 18 which has a piston rod102. Piston rod 102 is secured to flange 19 which supports cooling airring 20 via suitable L-shaped support arms 103, which support the airring 20 at a location around the slip segment portion of belling head17. Belling head 17 is removably secured to the threaded forward end offlange assembly 19, so it can be readily removed and replaced.

Because of the substantial forward travel of belling head assembly 19,when the assembly is moved to the extended position, additional supportis required to prevent bending of piston rod 102. This additionalsupport is provided by guide rods 104, secured to the rear flangeassembly 19 and which slide in support bearings 105 located respectivelyat each side of air cylinder 18 and secured to pedestal 101. In view ofthe above explanation, it will be apparent that cooling ring 20 remainsin the same position relative to belling head 17 throughout theadvancing and retracting movement of the belling head.

As shown at FIG. 5, cooling ring 20 has a diameter substantially greaterthan the diameter of the belling head. The cooling ring is mounted inconcentric relation to the belling head and includes a plurality ofnozzles 106 equally circumferentially spaced and extending generallyinwardly of ring 20 to direct cooling air toward the end of a pipe onthe belling head. To provide for a more compact apparatus, portion 107of the cooling ring is flattened so the heating head assembly 3 can beplaced closely adjacent belling head assembly 4 without interferenceduring movement of the respective heating and belling heads. Cooling airis supplied to the cooling ring from a suitable source of compressed airvia flexible hose 108.

Heating head 14 is mounted beside belling head assembly 4, as previouslyexplained. As shown at FIGS. 5-7, the heating head includes a hollowcylindrical shell 110 which is advantageously insulated to prevent heatloss. A cover plate 111 is secured to one end of the shell as by bolts112. Mounted within shell 110 is a heating element 113 which takes theform of a helically wound coil of a electrical heating element material.The several turns of the coil are maintained in spaced relation to eachother by a plurality of coil support elements 114 secured to andextending radially inwardly from the inside surface of shell 110 inequally spaced relation circumferentially of each other. The ends ofheating coil 113 extend through openings in the side of shell 110 tofacilitate connection to cables 115 from a suitable electric powersource.

Extending through cover plate 111 at its geometric center is a cleaningair nozzle 116. Nozzle 116 is provided with air from a suitable sourcevia the flexible hose 117.

As shown at FIGS. 2 and 5, heating head 14 is mounted on a cradle 120.Cradle 120 has a contour conforming to the arcuate configuration of thelower portion of shell 110 and is secured to the heating head in anysuitable manner, for example, by welding. A pair of bearings 121 aresecured to cradle 120. These bearings are spaced apart from each otherand have parallel axes. The bearings in turn are mounted on and slidablealong shafts 122, which are parallel with each other, spaced apart thesame distance as the axes of bearings 121, and rigidly secured to mainframe 40 at their opposite ends. Connected to the horizontal center ofcradle 120 is air cylinder 15 which moves the heating head to itsextended and retracted positions. The piston rod of cylinder 15 ispivotally connected to the cradle, and the opposite end of cylinder 15is also pivotally connected to main frame 40.

When cylinder 15 is activated to extend the piston rod, heating head 14slides forward along slide shafts 122 to the dotted line position of theheating head, as shown at FIG. 1. When cylinder 15 is operated toretract the piston rod, heating head 14 returns to its retractedposition, as shown in solid lines at FIG. 1.

As shown at FIGS. 8-10, belling head 17 includes a cylindrical body 125,a cylindrical nose 126, a slip segment assembly 127 and a limit switchtrip assembly 128. Body 125 is hollow and has a frusto-conical exteriorsurface 129. Advantageously, frusto-conical surface 129 extends at anangle of 5° with the axis of body 125. The frusto-conical surface 129terminates at a transverse annular front face 130 of body 125. At theother end, body 125 has an outwardly projecting cylindrical flange 131.Flange 131 has an annular groove 132 formed therein. The groove 132 isdefined by a cylindrical inner surface 133, a transverse annularshoulder 134, which faces toward nose 126, and the frusto-conicalsurface 129 terminates at shoulder 134.

Body 125 is hollow and has an internally threaded bore 135 at its flangeend, and via which belling head 17 is threaded onto and secured toflange assembly 19. In addition, there is a larger diameter threadedbore 136 to receive the externally threaded sleeve 137 of nose 126.

Nose 126 is formed with recess 138 which provides a transverse annularshoulder 139 that abuts the front face 130 of body 125. Recess 138 is soformed that a tapered circumferential lip overlaps the front end of body125. The lip has an inwardly facing frusto-conical surface 140 whichforms an acute angle of 20° with the axis of the belling head.

Slip segment assembly 127 is comprised of a plurality of slip segments141 and 142. The slip segments each have a length, as measured betweenfront shoulder 143 and rear shoulder 144 of the slip assembly, which issomewhat less than the distance between shoulder 139 and shoulder 134.Hence, the slip segment assembly is free to slide axially along conicalsurface 129 within the limits of the shoulders 139 and 134. The insidesurface 145 presented by the slip segments is frusto-conical and makesthe same 5° angle with the axis of the belling head as frusto-conicalsurface 129 of body 125.

When slip segment assembly 127 is in the position of FIG. 9, the slipsegments are in their expanded condition and present a cylindricalsurface 146 with a diameter corresponding to the internal diameter of abell to be formed on the end of a pipe. The tapered front portion 147 ofthe slip segments makes an angle of 20° with the axis of the bellinghead, and as will be recalled, this 20° angle is the same as the angleof inwardly facing surface 140 of nose 126. Hence, when slip segmentassembly 127 is moved toward nose 126, surface 140 acts on surface 147to contract the slip segments. The distance between rear edge 148 ofsurface 140 and surface 149 of flange 131 is slightly less than thelength of the slip segment assembly, so the slip segments can not falloff the assembled belling head.

As will be observed with reference to FIGS. 8-10, the slip segments 141differ from slip segments 142, in that each slip segment 141 has itssides 150 cut at an angle so the segment becomes circumferentiallynarrower in a direction toward flange 131. On the other hand each slipsegment 142 has its side edges 151 cut at an angle so the segmentbecomes circumferentially wider in a direction toward flange 131. Theside edges 150 are spaced from side edges 151, and a filler strip 152 ofuniform thickness and formed from a resilient material, such as rubber,is interposed between the side edges of adjacent slip segments. Thefiller strips 152 has a cross-sectional configuration the same as theconfiguration of the side edges of each slip segment. The purpose of theresilient filler strips to maintain the slip segments, which are free torotate on frusto-conical surface 129, equally spaced circumferentiallyof each other.

The respective side edges 150 and 151 of adjacent slip segments lie in aplane which intersects the axis of the belling head and forms a 5° anglewith the belling head. However, the planes defining the respective sideedges 150 of slip segments 141 converge, and hence, intersect at alocation beyond flange 131. On the other hand, the planes defining theside edges 151 of slip segments 142 converge, and hence, intersect, butat a location beyond nose 126.

Filler strips 152 are bonded to only one edge of each slip segment sothe facing edge of an adjacent segment is free to move relative to thefiller strip. Advantageously, the filler strip is of such a widthrelative to the dimension of the slip segments that the outside surface146 of the slip segment assembly is truly cylindrical and the taperedfront surface of the slip segment assembly is truly frusto-conical, whenthe slip segment assembly is in the expanded position of FIG. 9, withrear shoulder 144 in engagement with transverse shoulder 134. It is tobe noted with particularity, with reference to FIG. 9, that the distancebetween edges 150 and 151 and correspondingly, the width of filler strip152 is relatively narrow compared with the offset 153 of the side edgesof adjacent slip segments along the length of the cylindrical surface146. This offset assures that the bell formed on the end of a length ofpipe will have no internal ridges that could cause a leak between joinedlengths of pipe. Were it not for this offset, ridges could be formed onthe inside surface of the pipe. The expansion of the end of the pipe toform the bell 32 occurs as a result of straight line insertion of thebelling head into the heat softened end of the pipe. Initial engagementof the front end edge of a pipe with the slip segment assembly 127causes the slip segment assembly to move into engagement with shoulder134 so the slip segments are fully expanded, as shown at FIG. 9. Becauseof the offset 153 of the side edges of each slip segment, a particulararea of the inside surface of the pipe will be in engagement with afiller strip 152 for only a portion of its travel along the length ofcylindrical portion 146 of the slip segments, and hence, no internalridges are formed.

After the bell end 32 is formed on the pipe, air is forced through thecooling ring to cool the belled end while it is in engagement with theslip segment assembly 127. During such cooling, the bell end 32 of thepipe contracts. However, the slip assembly 127 remains in the positionshown at FIG. 9, because the 5° angle of frusto-conical surface 129 andinside surface 145 of the slip segments is self locking, and hence, theslip segments will not slide forwardly toward shoulder 139 when the bellend 32 contracts.

When bell end 32 is cooled to a temperature below the softeningtemperature of the material from which the pipe is formed, the bellinghead is withdrawn from the end of the pipe. During the initial movementof the belling head, slip segment assembly 127 remains in engagementwith and moves with the bell end of the pipe. Movement of the slipsegment assembly toward nose 126 allows the slip segment assembly tocontract to a diameter smaller than the inside diameter of bell 32 andsuch contraction is assisted by engagement of surface 140 with surface147. In addition, as the slip segments contract, the resilient fillerstrips 152 are compressed, which causes them to expand radially and"pop" the pipe free from the polished surfaces of the slip segments.Hence, the belling head is readily withdrawn from the belled end 32 ofthe pipe.

Limit switch trip assembly 128 (FIG. 10) is secured to flange 131. Thisassembly includes a mounting block 160 having a pair of parallelcounter-bore openings 161 with their axes parallel with the axis ofbelling head 17. Extending through each bore is a cap screw with anenlarged head 162, which extends into the bore. Between head 162 and ashoulder 163 of bore 161 is a compression spring 164. A trip plate 165is connected to the screws for movement therewith. As shown at FIGS.8-10, plate 165 is relatively thin and engages rear surface 159 ofmounting block 160 when springs 163 are relaxed.

Also carried by flange 131 is a limit switch 166. Limit switch 166 issecured to the rear face of flange 131 and has an operating arm 167.Extending through arm 167 is an adjusting screw 168 which is adjusted sothe switch is actuated when a pipe, completely seated on belling head17, engages the heads 162 of the screws with its end edge 169 and movesthem and the trip plate to the position of FIG. 9. In the fully seatedposition of the pipe, end edge 169 engages front face 149 of the flange131.

As shown at FIG. 3, pipe transfer device 10 includes a pair of uprightsupports 175. Adjustably mounted on each support 175 is a support block176. The connection between the support 175 and support block 176includes a threaded connection which provides for vertical adjustment ofthe support block. A V-shaped transfer member 177 is pivotally supportedon the support block by aligned pivot pins 178. The pivot pins supporttransfer member 177 for pivotal movement to and from the dotted lineposition of FIG. 3. Transfer member 177 is moved to and from thesepositions by a motor in the form of a pneumatically operated cylinder179. The rod of the cylinder is connected to an arm (not shown)extending downwardly from transfer member 177 to a location somewhatbelow the axis of pivot pins 178. The other end of cylinder 179 ispivotally supported on the frame of the belling apparatus. Hence, whencylinder 179 is actuated to extend its piston rod, pipe 5 is depositedon table 180 at the infeed side of the belling apparatus, and rolls fromtable 180 onto conveyor belts 8 and 9.

As shown at FIG. 3, outfeed conveyor 38 is positioned at the dischargeside of the belling apparatus. Advantageously, this conveyor includes anelongated stop fence 181 which arrests the transverse travel of the pipeon the continuously driven outfeed conveyor belt 182. Conveyor belt 182is driven by a motor 183 via a suitable drive mechanism, for example, achain and sprocket drive.

CONTROL SYSTEM

FIG. 11 shows the control system which operates belling apparatus 1 toform a bell end on a length of plastic pipe without manual assistance.The control system includes a source of pressurized air 185 to which airmotor cylinders 179, 73, 15, 78, 95, and 24 are connected via a header186 and suitable pipe or tubing. Control valves 187-192 are provided forthe respective cylinders. Each of control valves 187-192 is a four-wayvalve so connected to its cylinder that, in one position of the valve,air from source 185 is directed to the cylinder end and the piston rodend is vented, and in the other position of the valve air is directed tothe rod end and the cylinder end is vented. Each of the valves 187-192is solenoid operated. Valves 188 and 190 are so connected to therespective cylinders 73 and 78 that air from source 185 is directed tothe cylinder or head end when the solenoid is unenergized, and to thepiston rod end when the solenoid is energized. The valves 187, 189, 191and 192 are so connected to their respective cylinders that air issupplied to the piston end of these cylinders when the solenoids for thevalves are unenergized, and to the cylinder end when the solenoids areenergized.

Cleaning air nozzle 116 is also connected to air pressure source 185.Valve 193, connected in the supply pipe for air nozzle 116, is solenoidoperated and of the type which opens when its solenoid is energized andcloses when its solenoid is unenergized.

Similarly, cooling air ring 20 is connected to source 185. Solenoidoperated control valve 194 controls air flow to the cooling ring fromthe air pressure source. Valve 194 is solenoid operated and of the typewhich opens to supply air to the cooling ring when its solenoid isenergized, and closes when the solenoid is unenergized.

Cylinder 18, which controls the advance and retraction of the bellinghead, advantageously has a source 195 of pressurized air separate fromthe source for the other air motors of the belling apparatus. The valvearrangement for operating cylinder 18 is somewhat different from thevalves for the other air motors. Air is supplied to the head end ofcylinder 18 through a control valve 196 which is of the three-way type,and a similar valve 197 controls air flow to the piston rod end ofcylinder 18. Valve 196 is open and directs air to the head end ofcylinder 18 when its solenoid is energized, and closes and vents thehead end of the cylinder when its solenoid is unenergized. Valve 197,which controls air to the piston rod end of cylinder 18, works in thesame manner. Air flow to both the piston rod end and head end ofcylinder 18 is regulated by suitable pressure regulating valves 198 and199 in the air lines for the respective ends of cylinder 18.

The automatic operation of belling apparatus 1 is controlled by limitswitches which sense a length of plastic pipe at a particular location,and initiate the operation of timing devices which operate the severalair motors of the belling apparatus in a predetermined sequence. In thepreferred embodiment there are three limit switches. One is the switch166 which is mounted on belling head 17, the second is the switch 201which is located between stations 2 and 3 (FIG. 1) and the third isswitch 202 which is located between stations 3 and 4. Switch 201 islocated at a position beyond stop rods 25 and 26 so a pipe travelingfrom positioning station 2 to heating station 3 actuates the switch.Similarly, switch 202 is mounted beyond stop rods 27, 28 so a pipemoving from heating station 3 to belling station 4 operates switch 202.

Referring again to FIG. 11, switch 201 controls the operation ofsequence timer 203, switch 202 controls the operation of sequence timer204, and switch 166 controls the operation of timer 205. The solenoidcontrols for the several air motors, cooling ring, and cleaning airnozzle are connected to a suitable electrical power supply via theseveral timers 203-205. This power source can, of course, be the usual110 volt 60 cycle power supply.

DETAILED DESCRIPTION OF OPERATION

With the air motors of FIG. 11 in the positions shown, all the stop rods25-30 are retracted, transfer device 10 is in the position shown at FIG.3 where transfer member 177 is in its upright position, lift cradles 21and 22 are retracted, clamp 23 is retracted, heating head 14 isretracted, and belling head 17 is retracted. For purposes ofexplanation, assume that a pipe is manually deposited to conveyor belts8 and 9 which transport the pipe to the positioning station 2. Sincestop rods 25, 26 are retracted, the pipe is not stopped at positioningstation 2, but moves toward heating station 3. As the pipe travelstoward heating station 3, switch 201 is actuated by the pipe and theswitch initiates the operation of timer 203. As soon as switch 201 isactuated by the pipe, contacts 207 of the timer close to actuate valve188 which causes air to flow to the piston rod end of cylinder 73,thereby retracting the piston rod and moving stop rods 25-28 to theirelevated positions as shown at FIG. 1. After a short time delay,sufficient for the pipe to move into engagement with the now extendedstop rods 27, 28, which align the pipe with heating head 14, as shownfor the pipe 6 of FIG. 1, contacts 208 of timer 203 close and valve 189is actuated to admit air to the cylinder end of cylinder 15, therebyadvancing heating head 14 to the dotted line position of FIG. 1.Contacts 209 of timer 203 close shortly after contacts 208 close,sufficient time being provided for the heating head to move to itsadvanced position. When contacts 209 close, valve 193 opens and air isdirected through cleaning nozzle 116 to blow debris and other foreignmatter from the inside of the end of the pipe at the heating station.Contacts 209 open several seconds after they are closed to terminate thecleaning air blast. Contacts 208 remain closed for a sufficientpredetermined period of time to allow the heating head to heat the endof the pipe to its softening temperature. As previously explained, thepipe is rotated by the conveyor belts 8 and 9 at the heating station sothe end of the pipe is uniformly heated. After the elapse of the timefor heating, contacts 208 open, air to cylinder 15 is reversed, andheating head 14 is retracted. After a short delay of perhaps one-halfsecond, which provides time for the heating head to retract, contacts207 open, cylinder 73 is reversed to retract stop rods 25-28, and thepipe is then free to be conveyed toward belling station 4 by theconveyor belts.

As shown at FIG. 11, control switch 201 also controls switch 210 whichcontrols air cylinder 179 of transfer device 10. The arrangement is suchthat operation of switch 201 causes immediate operation of switch 210 sotransfer member 177 is pivoted to feed a pipe to the conveyor. Switch210 is advantageously of the time delay type which closes in response tooperation of switch 201, but remains closed for only several seconds.Hence, cylinder 179 is operated to pivot transfer member 177 and returnthe transfer member to its upright position after several seconds delay.Since stop rods 25-28 are moving toward their extended positions at thetime the transfer member is pivoted, the pipe so transferred will bemoved to positioning station 2 and will be held there in readiness fortransfer to heating station 3.

When stop rods 25-28 are lowered at the end of a heating cycle, the pipeis transported toward belling station 4 by the conveyor belts. (At thesame time, a pipe at station 2 is transported toward station 3 andactuates switch 201 to initiate another heating cycle at the heatingstation.) The pipe traveling toward station 4 actuates control switch202 which initiates the belling cycle. As soon as switch 202 isactuated, the operation of timer 204 is initiated.

Upon actuation of timer 204, contacts 211 immediately close so cylinder78 is actuated to move stop rods 29, 30 to the extended position ofFIG. 1. After a short time delay sufficient for the pipe to move intoengagement with the stop rods, contacts 212 close to operate cylinder 95which lifts lift cradles 21, 22 to elevate the pipe into precise axialalignment with the belling head. After another short time delaysufficient for the lift cradles to elevate, switch 213 closes to lowerclamp 23 which clamps the pipe against cradle 22. Contacts 214 close atabout the same time as contacts 213. When contacts 214 close, valve 196opens to admit air to the cylinder end of cylinder 18, and therebyadvance belling head 17. As the belling head advances, it enters theheat softened end of the pipe on the lift cradles. Initial engagement ofthe end of the pipe with slip segment assembly 127 causes the slipsegment assembly to move to the position of FIG. 9 in which the slipsegments are expanded. Further movement of the belling head forces thehead into the end of the pipe so a cylindrical bell is formed. Duringthis belling operation, axial movement of the pipe is resisted primarilyby rear fence 13. When the pipe is fully seated on the belling head, asshown at FIG. 9, and edge 196 engages the limit switch trip assembly andoperates limit switch 166. Limit switch 166 immediately opens switch 215which closes valve 196 and vents the cylinder end of cylinder 18. Hence,further forward movement of the belling head is immediately terminatedwhen switch 166 is actuated.

Actuation of switch 166 initiates the cycle of operation of timer 205.As soon as switch 166 is actuated, contacts 216 of timer 205 close toopen valve 194 and supply air to cooling ring 20. Air from the coolingring is directed toward the bell end 32 of the pipe while the pipe is onthe belling head as shown at FIG. 9. After a predetermined period oftime sufficient for bell end 32 to cool below its softening temperature,contacts 216 open and close valve 193. Simultaneously, contacts 217close to actuate valve 197 which admits air to cylinder 18 to retractbelling head 17. During the initial retracting motion of belling head17, slip segments 127 move relative to body 125 to the position of FIG.10, where the slip segments are in a contracted condition. With thesegments so contracted, the surface presented by the segments is smallerthan the inside diameter of bell 32, and belling head 17 can be readilywithdrawn from the belled end of the pipe. After a time delay sufficientfor withdrawal of belling head 17, timer 205 opens switch 218 whichreverse valve 192 and causes cylinder 24 to lift clamp 23.Simultaneously, contacts 219 open, thereby reversing cylinder 95 so liftcradles 21, 22 are lowered and the pipe is deposited on conveyor belts 8and 9. Then, timer 205 opens contacts 220 which reverses cylinder 78 andretracts stop rods 29, 30. The pipe with the bell end formed thereon isthen conveyed by conveyor belts 8 and 9 to outfeed conveyor 182 whichcarries the belled pipe away from the apparatus.

The pressure regulators 198 and 199 are provided for cylinder 18 toregulate the pressure and air flow to the cylinder during advancemovement and retracting movement of belling head 17. It is desirable toadvance the head relatively slowly, or at a controlled rate, and suchcontrol is provided by the regulator 199. In addition, when the head isretracted, it is also desirable to control the rate of retraction andthis is accomplished by the regulator 198.

SECOND EMBODIMENT

FIGS. 12-14 show a second embodiment of the bell end forming apparatusof this invention. The second embodiment is quite similar to the firstembodiment, in that apparatus 220' as shown at FIG. 12, includes aninfeed conveyor 11 which moves pipe to a transfer device 10 from whichit is transferred to conveyor belts 8 and 9 which convey the pipetransversely of its length. Apparatus 220' includes a positioningstation 2 identical to the positioning station described for the firstembodiment, but which differs from the first embodiment in that there isa combined heating and bell end forming station 221. Station 221includes a belling head 17 having an air cooling ring 20 moved by an airmotor 18, these parts and their operation being identical to thatdescribed for the first embodiment. At station 221, there is also a liftmechanism including cradles 21 and 22 identical to those described forthe first embodiment, and a clamp 23 also identical to that describedfor the first embodiment.

At station 2, there are stop rods 25 and 26 the same as those describedfor the first embodiment, and there are stop rods 222 and 223 which areidentical to the stop rods 27 and 28 at heating station 3 of the firstembodiment, and which are moved in unison with the stop rods 25 and 26.Station 221 also has a heating head 224, but this heating head differssubstantially from the heating head 14 of the first embodiment. Heatinghead 224 is comprised of two semi-circular half sections 225, 226 whichare separate from ech other. Shell 225 has a heating element 227 andshell 226 has a heating element 228. In addition, an air cleaning nozzle229 is mounted on back plate 230 of shell 226 to direct cleaning airthrough the pipe prior to forming a bell end on the pipe.

Shell 225 is connected to an air motor in the form of a cylinder 230which has its axis vertical and extends upwardly above the shell. Shell226 is connected to the piston rod of an air motor in the form of acylinder 232 with its axis vertical, and which extends downwardly belowshell 226. Cylinders 231 and 232 operate in unison to move therespective shells 225 and 226 from the retracted position, shown insolid lines at FIG. 13 (and also shown at FIG. 14) to the advancedposition shown in dotted lines at FIG. 13 where the half shells 225 and226 abut each other to form a cylindrical heating head to heat softenthe end of the pipe before the bell end is formed on the pipe.

OPERATION - SECOND EMBODIMENT

The operation of the second embodiment of the apparatus at pipe transferdevice 10 and at positioning station 2 is the same as for the firstembodiment, in that pipe is deposited on the conveyor belts, ispositioned at station 2, and is held in readiness for transfer to thenext station. When stop rods 25, 26 are retracted, pipe 5 is conveyedtoward station 221. During travel toward station 221, control switch 234is actuated which causes stop rods 25, 26, as well as stop rods 222, 223to be moved to their extended positions, as shown at FIG. 12. Switch 234also initiates a heating cycle at station 221 which includes actuatingcylinders 231 and 232 to move half shells 225 and 226 to the dotted lineposition of FIG. 13, so tha half shells comprise a heating drum whichsurrounds front end 16 of a pipe engaging stop rods 222, 223 at station221. The half shells 225, 226 are so extended that the horizontal planewhere the half shells meet lies in a horizontal plane passing throughthe axis of a pipe at station 221. Immediately after half shells 225 and226 close around the pipe, an air blast is directed through nozzle 229to clean the inside of the end of the pipe at station 221. Since thepipe still engages conveyor belts 8 and 9, the pipe is rotated while inengagement with stop rods 222 and 223, (in the manner previouslyexplained for the first embodiment), and correspondingly, end 16 of thepipe is uniformly heated during the heating operation.

After a sufficient length of time to heat end 16 to its softeningtemperature, half shells 225 and 226 are retracted, and retraction ofhalf shells initiates a belling operation identical to that describedfor the embodiment of FIG. 1, in that cradles 21, 22 are actuated tolift the pipe into axial alignment with belling head 17, clamp 23 islowered, the belling head is advanced to form the bell end on the pipe,limit switch 166 operates to control the length of the bell end formedon the pipe, cooling ring 20 cools the pipe while on belling head 17,the belling head is retracted after termination of the coolingoperation, clamp 23 is lifted, cradles 21, 22 are lowered, and stop rods222, 223 are retracted to allow conveyor belts 8 and 9 to transfer thepipe to outfeed conveyor 31.

When stop rods 222, 223 are lowered, stop rods 25, 26 are simultaneouslylowered and a pipe at station 2 is released for transfer by conveyorbelts 8 and 9 to the station 221.

While several preferred embodiments of an apparatus for automaticallyforming a bell end on a length of thermoplastic pipe have been shown anddescribed in detail, and while a preferred bell end forming arrangementhas also been shown and described in detail, it is to be understood thatnumerous changes and substitutions can be made without departing fromthe scope of the invention as defined herein and in the appended claims.

We claim:
 1. Apparatus for forming a bell end on a thermoplastic pipecomprising, in combination:endless conveyor means for conveying a pipein a direction transversely of its length; means defining first andsecond work stations along said conveyor means; heating means adjacentone side of said conveyor means at said first work station for heating,and therefore softening, an end of a pipe conveyed thereto; a bellforming device adjacent said one side of said conveyor means, spacedfrom said heating means in the direction of travel of a pipe on saidconveyor means and located at said second work station for belling theheated end of a pipe conveyed thereto; said means defining said firstwork station including first means, adjacent said conveyor means, forpositioning a pipe in alignment with said heating device at said firstwork station; said means defining said second work station includingsecond means, adjacent said conveyor means, for positioning a pipe inprecise axial alignment with said bell forming device at said secondwork station; means, adjacent said bell forming device and at saidsecond work station, for providing relative axial movement, andtherefore engagement, between said bell forming device and the heatsoftened end of the pipe to form a bell end thereon; first controlmeans, coupled to said first means for positioning and responsive tomovement of the pipe, for actuating said first means for positioning toalign the pipe with said heating means where the pipe end is heated, andfor deactuating said first means to allow the pipe to leave said firstwork station; and second control means, coupled to said second means andto said means for providing relative axial movement and responsive tomovement of the pipe towards said second work station, for actuatingsaid second means to align the pipe with said bell forming device, andfor actuating said means for providing relative axial movement to movesaid bell forming device and the pipe into engagement.
 2. Apparatusaccording to claim 1 wherein the apparatus further includesmeans to coolthe bell end formed by the belling device.
 3. Apparatus according toclaim 1 wherein the apparatus further includesmeans to clean the insideof the pipe prior to forming said bell end.
 4. Apparatus according toclaim 3 wherein said cleaning means includesmeans to direct a blast ofair through the pipe.
 5. Apparatus according to claim 1 whereinsaidconveyor is continuously driven; said stop means is movable betweenanextended position in which transverse movement of a pipe on saidconveyor is stopped by engagement with the stop means, and a retractedposition in which the pipe is moved to the second station by theconveyor; said conveyor contacting said pipe to rotate same while inengagement with said stop means to insure uniform heating of the end tobe belled.
 6. Apparatus according to claim 5 whereinsaid conveyor meansis a motor driven belt conveyor; said conveyor is mounted on a conveyorframe; said motor is mounted on said conveyor frame; and said conveyorframe is mounted on said belling apparatus for vertical adjustmentrelative to said heating device and bell forming device; whereby, saidconveyor can be adjusted vertically to properly position pipe ofdifferent diameters relative to said heating device.
 7. Apparatusaccording to claim 1 whereinsaid positioning means includessecond stopmeans to generally align a pipe with said bell forming device, and liftmeans to precisely align the pipe with the bell forming device. 8.Apparatus according to claim 7 wherein said second stop means is movablebetweenan extended position to stop a pipe at the second station, and aretracted position in which the pipe is conveyed away by the conveyormeans, and said lift means includes first and second lift cradlesengaging a pipe at axially spaced locations to lift the pipe intoalignment with the bell forming device.
 9. Apparatus according to claim1 whereinsaid apparatus further includesmeans to automatically terminateoperation of said motor means for said bell forming device in responseto a predetermined extent of engagement of pipe with the forming device;whereby, a bell of the same length is formed on the end of successivelybelled pipe irrespective of variations in length and position of thepipe relative to the belling head.
 10. Apparatus according to claim 1whereinsaid heating means is electrically heated and includesacylindrical shell, and an electric heating element supported adjacentthe inner cylindrical surface of the shell; said heating means includesmotor means for moving said shell to a position surrounding the pipe endto heat same to its softening temperature; and a cleaning air nozzle issupported along the axis of the shell to clean the pipe end prior to thebell forming operation.
 11. Apparatus according to claim 1 which furtherincludesa positioning station before said first and second work station,said positioning station includingspaced apart guide means to axiallyposition a pipe on the conveyor means, and additional stop means tomaintain the pipe in spaced relation to said first work station. 12.Apparatus according to claim 1 which further includesinfeed means tointermittently feed a length of pipe to said conveyor means; and outfeedmeans to transport belled pipe away from the belling apparatus. 13.Automatic pipe belling apparatus comprisingmeans defining first andsecond work stations; heating means at said first work station; bell endforming means at said second work station; endless conveyor means fortransporting a pipe to said first and second work stations; said meansdefining said first work station including first positioning means,adjacent said conveyor means, for aligning a pipe with said heatingdevice at said first work station; first control means, coupled to saidfirst positioning means and responsive to movement of said pipe foractuating said first positioning means; said means defining said secondwork station including second positioning means, adjacent said conveyormeans, for aligning a pipe with said bell forming means at said secondwork station; second control means, coupled to said second positioningmeans and said bell end forming means and responsive to movement of saidpipe from said first work station to said second work station, foractivating said second positioning means, and providing relativemovement between said bell end forming means and the heat softened endof the pipe to produce engagement therebetween; cooling means at saidsecond work station to cool said bell end; and means for sequentiallyseparating said bell end forming means and said pipe and transportingthe pipe away from the second work station.
 14. Apparatus according toclaim 13 whereinsaid conveyor is continuously driven; said firstpositioning means includes stop meansextendable to stop said pipe inalignment with said heating means while permitting rotation of the pipeby said conveyor, and retractable to allow the conveyor to transport thepipe to said second station; said heating means is movablefrom aretracted position, spaced from a pipe at the first station, to anextended position adjacent the end of the pipe; and motor means movessaid heating means to the extended and retracted positions. 15.Apparatus according to claim 14 whereinactuation of said first controlmeans initiates a sequence of operations includingextending said stopmeans, actuating said motor means to move said heating means to itsextended position, maintaining said heating means extended and adjacentthe pipe end to heat same, actuating said motor means to move saidheating means to its retracted position, and retracting said stop meansafter said heating means is retracted.
 16. Apparatus according to claim13 whereinsaid bell forming means is movablefrom a retracted positionspaced from the end of a pipe at said second station, to an extendedposition engaging the end of a pipe at said second station; motor meansmoves said bell forming means to the extended and retracted positions;which further includesthird control means, to deactivate said motormeans to terminate movement of the bell forming means toward theextended position, in response to a predetermined extent of engagementof said bell forming means with said pipe end.
 17. Apparatus accordingto claim 16 whereinsaid third control means includes a limit switchcarried by said bell forming means and operable in response toengagement of the end of the pipe.
 18. Apparatus according to claim 16whereinsaid second positioning means includes second stop means movabletoan extended position to stop a pipe at said second station, aretracted position in the conveyor conveys the pipe away from the secondstation, and said second positioning means further includes pipe liftmeans movableto an extended position to lift a pipe engaging said secondstop means to a position in alignment with said bell forming means, andretraction of the bell forming means after cooling the bell end, andlowering of the lifting means to its retracted position after retractionof the bell forming means.
 19. Apparatus according to claim 18 whichfurther includesinfeed transfer means to transfer a pipe to saidconveyor means in response to actuation of said first positioning means.20. Apparatus according to claim 13 which further includesa positioningstation before said first work station; means at said positioningstation to align a pipe relative to the conveyor; and stop means toselectively retain a pipe at said positioning station.